1. Field of the Invention
The present invention relates to a curved suspended ceiling having a grid of inverted T beams suspended from a structural ceiling, with drywall boards fastened to the grid.
2. Description of the Prior Art
Suspended ceilings in rooms are common. They have a grid of metallic beams that is suspended from an overhead structural ceiling, as by wires.
The metallic beams used in the grids of suspended ceilings are made in a continuous process. A continuous strip of metal, usually steel, fed off a reel, is passed through a series of rolls that form the metal into an inverted T cross section having a web, a bulb at the top of the web, and horizontal flanges extending from the bottom of the web. Such beam construction is well-known.
A straight, finished beam continuously emerges from the roll forming operation, and is cut, on the run, into suitable lengths, of, for instance, 12 feet, or 4 feet, or 2 feet, with, for instance, a flying shear. Connectors are then formed at the ends of the straight beam lengths. The beams are then stacked and packaged for shipment to the job site for assembly into the grid of a suspended ceiling. The beam cross section gives the beam rigidity throughout these operations.
The beams are formed into a grid at the job site, in the well-known prior art manner, by means of the connectors at the ends of the beam. Such grid has parallel main beams that are connected by cross beams.
In a panel suspended ceiling, panels are laid in the grid openings and supported by the flanges of the beams. In a drywall suspended ceiling, drywall boards are attached to the beams of the grid by screws.
Both types of ceilings described above virtually always extend in a horizontal plane.
Occasionally, suspended ceilings that are curved are installed, particularly of the drywall type. In a curved drywall suspended ceiling, a grid of curved main beams, connected by straight cross beams, is suspended by wires from a structural ceiling, and drywall boards are then attached to the grid by screws, as in a horizontal drywall suspended ceiling. The faces of the drywall boards are wetted and then are bent to the desired shape prior to attachment to the grid.
There are various prior art ways of forming a curved main beam for use in the grid of a curved drywall ceiling.
In U.S. Pat. No. 6,751,922 issued Jun. 22, 2004, for FACETED RADIUS GRID, incorporated herein by reference, the prior art is discussed, and there is disclosed an improved curved main beam, wherein straight, inverted T beams are continuously roll formed from strip metal, at the factory, in the usual prior art way.
Such beams are of inverted T cross section with a bulb at the top, a downward extending vertical web, and horizontal flanges extending from the bottom of the web. The two layers of the web are continuously stitched together. Cutouts in the beam, at spaced intervals along the beam, are made continuously and contemporaneously with the roll forming operations, in a portion of the web and a bulb. A segment of the bulb is left in place above the cutout to maintain the integrity of the straight beam. The cutouts are manually extended through the remaining segment of the bulb at the job site with a minimum of cutting and no need for measuring, and the beam is bent to the required radius, at the cutouts, between facets. Splice plates are applied over the extended cutouts at the bend to fix the beam at the desired faceted curve.
Drywall boards are then attached, from underneath the ceiling, to the beam flanges, as by self-tapping screws. In applying the drywall to the grid, the faces of the drywall boards are wetted, and then are curved to the desired shape to conform to the faceted grid, prior to attachment to the grid.